Built-in television console antenna

ABSTRACT

Two single turn horizontally oriented loops are located in a common plane inside a television receiver cabinet. A multiposition switch is used to connect the loops in various combinations to the receiver antenna terminals. In a typical receiver, employing separate VHF and UHF tuner inputs a fourposition switch is employed. In one position one loop is connected to the VHF input and the other is connected to the UHF input. In the second position the loops are exchanged. In the third position both loops are connected to the VHF input and in the fourth position both loops are connected to the UHF input. Thus for either VHF or UHF reception the user has a selection of three switch positions for optimum signal pickup.

"United States Patent Verma et al.

BUILT-IN TELEVISION CONSOLE ANTENNA Inventors: Jugal K. Verma,Conshohocken;

Buran I. Keprta, Jr., Norristown, both of Pa.

Assignee: Aeronutronic Ford Corporation,

Blue Bell, Pa.

Filed: Mar. 25, 1974 Appl. No.: 454,175.

References Cited UNITED STATES PATENTS Spindler 343/702 3,261,019 7/1966Lundy 343/876 Primary Examiner-Eli Lieberman Attorney, Agent, orFirm-Robert D. Sanborn [5 7] ABSTRACT Two single turn horizontallyoriented loops are located in a common plane inside a televisionreceiver cabinet. A multi-position switch is used to connect the loopsin various combinations to the receiver antenna terminals. In a typicalreceiver, employing separate VHF and UHF tuner inputs a four-positionswitch is employed. In one position one loop is connected to the VHFinput and the other is connected to the UHF input. In the secondposition the loops are exchanged. In the third position both loops areconnected to the VHF input and in the fourth position both loops areconnected to the UHF input. Thus for either VHF or UHF reception theuser has a selection of three switch positions for optimum signalpickup.

8 Claims, 8 Drawing Figures PATENTEU SEP 1 61975 lid BUILT-IN TELEVISIONCONSOLE ANTENNA BACKGROUND OF THE INVENTION A satisfactory built-intelevision receiver antenna has long been sought by the industry butcomplete success has not been achieved. One major problem is the broadrange of signal frequencies that must be picked up. Currently in theUnited States three bands are involved. These are: low VHF-54 to 88 MHz;high VHF- 174 to 216 MHZ; and UHF-470 to 890 MHz. A tuning range of over16 to l is involved. This alone presents formidable problems in anantenna system and these problems are made much more difficult if theantenna is to be confined to the inside of the television receivercabinet.

Optimum reception is achieved by using an outside antenna system,mounted above the building and adjusted for satisfactory operation.However, in strong signal areas, such as those normally found inmetropolitan areas, indoor antennas can often provide satisfactoryreception. The most popular indoor antennas are the telescoping dipoleor monopole for VHF reception and a movable loop or a bowtie for UHFreception. Such antennas are unsightly and are cumbersome to adjust.They are susceptible to breakage and often develop poor electricalconnections because of the sliding contacts involved.

The most desirable form of indoor antenna is one that is sufficientlycompact to mount inside the conventional receiver cabinet. In the priorart dipoles of various configurations have been stapled or otherwisefastened inside the cabinet or fastened to the removable back cover. Insome cases elaborate tuning devices were employed to make the antennassufficiently responsive. Usually such antennas need orientation becauseof their directional response and this necessitates moving the receivercabinet, often to a position that is quite unsuitable for viewing.Ordinarily the receiver cabinet is not large enough to accommodate anantenna that is rotatable.

To achieve the effect of rotation without actually moving the antenna ithas been proposed to make the antenna in the form of four elementsdisposed at 90 with respect to each other and having a common center.The four elements are connected to a switch that is arranged to connectthe four elements in various configurations to the receiver antennaterminals. This effectively rotates the antenna pattern but at eachposition the antenna is resonant to a particular frequency. Thus suchantennas are too narrow band to be of use over all of the televisionbands.

In short none of the prior art antennas associated directly with thetelevision receivers, whether built in or attached to the cabinet, haveproven to be very satisfactory.

SUMMARY OF THE INVENTION It is an object of the invention to provide abuilt-in television receiving antenna that is sufficiently broad band tocover both VHF and UHF bands and needs no physical orientation.

It is a further object to provide an antenna that can be securedunobtrusively inside a television receiver cabinet, and to provideelectrical manipulation of performance in order to obtain most suitableoperation.

' These and other objects are achieved in the following manner. Twobroadband single-tum loop antennas are secured in close mutual proximityto the inside of the top of the receiver cabinet. The loops arehorizontal and in the same plane. The loops are of a size that setstheir fundamental reasonance to just above the high VHF band, whichplaces their second harmonic just below the UHF band. Fundamentalresonance occurs when the perimeter of the loop is one electricalwavelength. The loops are made square with flat sides adjacent. Thisconfiguration makes the pair conform 'easily to the conventionalrectangular television console cabinet shape. The loops are connected,by means of conventional 300-ohm ribbon leads, to a multi-positionswitch which in turn is connected, by means of similar ribbon leads, tothe VHF and UHF antenna terminals on the receiver. The switch permitsconnecting the loops in various combinations to the two tuner inputs. Inthe preferred embodiment a four position switch provides the followingloop connection permutations. In position number 1, one loop isconnected to the VHF tuner and the other loop is connected to the UHFtuner. In position number 2 the loops are exchanged. In position number3, both loops are connected together tothe VHF tuner. In position 4,both loops are connected together to the UHF tuner. Since the loopsinteract with each other and with the underlying, adjacent televisionreceiver, their normally smooth omnidirectional pickup patterns willhave lobes and nulls. By providing the user with three selections eachfor VHF and UHF operation, the patterns can be modified so the user canselect the position of best performance.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows the antenna mounted in atelevision cabinet which is shown in phantom View;

FIG. 2 shows the essential elements of the antenna system; and

FIGS. 3-8 show the response, at six different frequencies; of theantenna mounted inside a convention console television receiver.

DESCRIPTION OF THE INVENTION FIG. 1 shows a television receiver cabinet10 in phantom outline. Square loops 1] and 12 are mounted, by means notshown, inside the top of the cabinet so as to be fully contained andconcealed therein. Each loop is about 35 cm. across thereby making theperimeter about 1.4 meters. The loops are about 2 to 10 cm. apart. Thefundamental loop resonance is about 230 MHz, or just above the high endof the high VHF band. The second harmonic is about 460 MHz, or justbelow the UHF band. The loop is made about 2.5 cm. wide and desirablycan be made from sheet stock. Where thin metal stock is used, the edgescan be rolled to make the structure more rigid. The ends of the loop aretapered, as shown, to reduce the terminal shunt capacitance. The openends are held in position by insulators at 13 and 14. The insulators canbe cemented or riveted to the loop.

The loop as described appears capacitive at the VHF channels. At UHF itacts as a multiresonant loop, passing through one resonance, the thirdharmonic, at about television channel 50. In the horizontal plane such aloop will be omnidirectional under free space conditions. Inside atelevision receiver cabinet, the loop will interact with the chassis,cathode ray tube components, wiring, and other outboard components.Accordingly, the omnidirectional pattern will be substantially modified,particularly at the higher frequencies. For example in a typicalsituation the antenna pattern will be largely omnidirectional at channel2 but will show a triple lobed response having a substantial change insignal response as a function of angle, at channel 83.

In the dual loop configuration, as shown in FIG. 1, the loops aredisplaced with respect to each other in azimuth so that any lobingpatterns will be relatively shifted by about 90. If one were to switchfrom one antenna to the other it would be as if the first antenna werephysically turned to a quadrature orientation.

Switch is interposed between the loops and the receiver antenna terminal16. The switch is connected to the receiver antenna terminals 16 bymeans of ribbon leads l7 and 18 to VHF and UHF inputs respectively.Ribbon leads 19 and connect the two loops to switch 15.

FIG. 2 shows the details of the action of switch 15. The following listdetails the connection available by means of the four positions.

Position 1: Loop 11 is connected to the VHF terminals and Loop 12 isconnected to the UHF terminals. Position 2: Loop 11 is connected to theUHF terminals and Loop 12 is connected to the VHF terminals. Position 3:Loops 11 and 12 are connected in parallel to the VHF terminals.

Position 4: Loops l1 and 12 are connected in parallel to the UHFterminals.

From the above it can be seen that for either VHF or UHF operation threeconditions are available. These include either loop alone or theparallel combination or both. As described above, when switching fromone loop to the other the antenna lobing pattern is shifted by about 90.The third position or parallel connected loops provides still anotherlobe pattern which is a complex combination of the patterns of theseparate loops. In the parallel connection the loops should be connectedin the in-phase terminal relationship.

It will be noted that when the receiver is set for VHF the unused loopin Positions 1 and 2 will be connected to the UHF tuner which will actas a line termination. Thus not only do the loops interact with thetelevision receiver components, they interact with each other because oftheir proximity and in accordance with the lead length and the nature ofthe lead termination. Thus while the leads connecting loops 11 and 12 toswitch 15 should have the same length, this length can be selected orvaried to modify the antenna patterns.

EXAMPLE A television console receiver, using a V display, had loopsinstalled, as described above and shown in FIG. 1. The receiver wasoperated in a variety of locations so as to produce a wide range ofsignal reception conditions. In addition, measurements of antennaperformance were made and polar plots of signal response were developed.

FIG. 3 shows the separate and combined loop responses at Channel 2. Itwill be noted that the patterns are almost those of free space loops,thereby showing only moderate interaction with the chassis and othercomponents.

FIGS. 4 and 5 show loop performance at VHF Channels 7 and 13respectively. FIGS. 6, 7, and 8 show the UHF responses at Channels 14,42, and 83. As the higher frequencies are approached, it will be notedthat the departure from free-space loop performance increases. FIG. 8clearly shows that the antenna has three well defined lobes and thelobes vary for each of the three loop configurations.

The bandwidth characteristics of the antenna were excellent therebymaking it useful for color television reception. In areas of strongtelevision signals the antenna performed as well as the conventionaltelescoping dipole and UHF loop combination. It was noted that the loopsproduced signals that were much less affected by adjacent environmentalconditions such as people moving about and metal structures such aslamps and other appliances. On most channels, particularly the high-bandVHF and UHF channels, the antenna could be switched to miminize ghostreception without moving the receiver. In general highly satisfactoryreception was obtained in most cases with the fully built-in antenna.

The antenna of the invention and its performance have been described.Alternatives and equivalents will occur to persons skilled in the art.For example, the loops have been shown as square whereas they can bemade round if adequate space is available inside the receiver cabinet.Rectangular or trapezoidal shapes could be used to conform the antennawith cabinet shape. Also ribbon lead connection cables have been shown,whereas each loop could be connected to a balun and a -ohm coaxial cableinterconnection used. Accordingly, it is intended that the invention belimited only by the following claims:

We claim:

1. A built-in antenna for receiving signals in a television receiverhaving separate VHF and UHF tuners, said antenna comprising:

A pair of single turn loops adapted for mounting horizontally in spacedapart side by side relationship and in a common plane inside the cabinetof said receiver, and

means including a switch for connecting said loops to said receiver incombinations including either of said loops singly to either of saidtuners and both of said loops connected together to either of saidtuners, said switch being positionable for best signal reception.

2. The antenna of claim 1 wherein said switch has four positions, thefirst position arranged to connect the first loop of said pair to saidVHF tuner and the second loop of said pair to said UHF tuner, the secondposition arranged to connect the first loop of said pair to said UHFtuner and the second loop of said pair to said VHF tuner, the thirdposition arranged to connect said pair of loops to said VHF tuner, andthe fourth position arranged to connect said pair of loops to said UHFtuner.

3. The antenna of claim 2 wherein said loops have a fundamentalresonance at a frequency slightly higher than the highest VHF televisionchannel.

4. An antenna built into a television receiver having separate VHF andUHF input terminals, said antenna comprising:

first and second loops disposed horizontally and in a common planeinside said receiver, said loops being oriented in azimuth atapproximately right angles with respect to each other, and

means, including a multiposition switch, for connecting said loops tosaid input terminals, said switch having positions which provide forconnections in- 6. The antenna of claim 5 wherein said parallelconnections connect said loops in phase with each other. 7. The antennaof claim 6 wherein said loops have a fundamental resonance of afrequency in the spectral region between the VHF and UHF televisionbands.

8. The antenna of claim 7 wherein said switch has four positions forproviding the recited connection combinations.

1. A built-in antenna for receiving signals in a television receiverhaving separate VHF and UHF tuners, said antenna comprising: A pair ofsingle turn loops adapted for mounting horizontally in spaced apart sideby side relationship and in a common plane inside the cabinet of saidreceiver, and means including a switch for connecting said loops to saidreceiver in combinations including either of said loops singly to eitherof said tuners and both of said loops connected together to either ofsaid tuners, said switch being positionable for best signal reception.2. The antenna of claim 1 wherein said switch has four positions, thefirst position arranged to connect the first loop of said pair to saidVHF tuner and the second loop of said pair to said UHF tuner, the secondposition arranged to connect the first loop of said pair to said UHFtuner and the second loop of said pair to said VHF tuner, the thirdposition arranged to connect said pair of loops to said VHF tuner, andthe fourth position arranged to connect said pair of loops to said UHFtuner.
 3. The antenna of claim 2 wherein said loops have a fundamentalresonance at a frequency slightly higher than the highest VHF televisionchannel.
 4. An antenna built into a television receiver having separateVHF and UHF input terminals, said antenna comprising: first and secondloops disposed horizontally and in a common plane inside said receiver,said loops being oriented in azimuth at approximately right angles withrespect to each other, and means, including a multiposition switch, forconnecting said loops to said input terminals, said switch havingpositions which provide for connections including, said first loopconnected to said VHF input and said second loop to said UHF input, saidsecond loop connected to said VHF input and said first loop connected tosaid UHF input, said first and second loops connected in parallel tosaid VHF input, and said first and second loops connected in parallel tosaid UHF input.
 5. The antenna of claim 4 wherein said loops areconstructed of strips of sheet metal having substantial width to providebroadband performance.
 6. The antenna of claim 5 wherein said parallelconnections connect said loops in phase with each other.
 7. The antennaof claim 6 wherein said loops have a fundamental resonance of afrequency in the spectral region between the VHF and UHF televisionbands.
 8. The antenna of claim 7 wherein said switch has four positionsfor providing the recited connection combinations.